1. Field of the Invention
The invention relates to a magnetically journalled rotational arrangement including a substantially disc-shaped or ring-shaped magnetically journalled rotor and stator.
2. Description of the Prior Art
Magnetically journalled rotational arrangements are used today in numerous fields of application, in particular, where mechanically journalled rotational arrangements have considerable disadvantages, thus e.g., in stirrers or forwarding apparatuses for highly pure or biological liquids such as, for example, blood. Magnetically journalled rotational arrangements are also useful in applications such as clean room blowers or carrier apparatuses for wafers (so-called wafer carriers) where high demands are placed on cleanliness and no contamination, such as is caused e.g., by gases which can escape from the lubricants of mechanical bearings, may be tolerated. In these applications, both the journalling of the rotor (which can be designed, e.g., as the vaned wheel of a pump) and a rotational movement of the same must be possible.
A magnetically journalled rotational arrangement with a flywheel is described in EP-A-0,130,541. Apparatuses of this kind are used, for example, in the control of the orientation of satellites. Ring-shaped permanent magnets for the magnetic journalling of the rotor are provided both in the rotor and in the stator; moreover the stator also comprises control windings in order to be able to correct possible deflections of the rotor from the desired position. Further separate drive means for driving the rotor are also provided in the rotor and in the stator. This has the result that the total construction is relatively complicated and expensive.